Edmonton releases flood maps for 100 neighbourhoods

Edmonton made history Wednesday by being the first Canadian municipality to give residents access to home-specific flood history and predictions for overland flooding.

Americans are able to access a detailed home insurance claim history for any property they own through LexisNexis. But Canada has no similar program and insurance companies guard their histories for competitive advantage.

On Wednesday, Edmonton was forced by Postmedia’s Freedom of Information request to disclose its maps, which are not related to flooding caused by the river. Officials also added a complete set of flood reports for each upland home dating back to 1946, and outlined the sewers they expect to reach capacity in a 1-in-100-year flash flood, causing backups into basements.

Those maps — with red zones in many neighbourhoods spanning several city blocks — are now publicly available at edmonton.ca/floodmitigation.

But branch manager Chris Ward has a note of caution for anyone who finds their home at risk. “Don’t panic. This is a worst-case scenario.”

A flood prediction map released by the City of Edmonton Nov. 9, 2016.City of Edmonton

Officials used high-resolution topographic maps of the flat table-lands high above Edmonton’s river valley. They matched it with sewer data and ran computer simulations of 1-in-100-year flash flood events, which have a one per cent chance of happening each year.

It’s the first time they’ve been able to predict flooding, not just react to soggy basements.

As expected, many of the worst areas are located where prairie sloughs once lay, said Ward.

“You will see this very clearly on the flood map,” he said, pointing to a large red blob in McKernan. “These are locations where we built residential neighbourhoods in the bottom of a lake bed without filling it in.”

Postmedia asked for those maps last spring, arguing residents have a right to know their risk. When the city declined, it appealed to the province and won.

On Wednesday, Ward said no other municipality has released this information to its residents, likely because Edmonton is farther ahead than other jurisdictions in its mapping effort.

Craig Stewart, vice-president at the Insurance Bureau of Canada, has also said Edmonton is the first Canadian jurisdiction to do this. His own organization has a nationwide map it intends to release but is worried about potential controversy.

Councillors get their first look at Edmonton’s neighbourhood-level flood maps Nov. 9, 2016, after Postmedia successfully fought for the information.Elise Stolte, Postmedia Network

City council got its first look at the maps Wednesday, too. There are bad patches across the city — in Lauderdale southeast of the Lauderdale School, in Ottewell one block north of Braemar School and a series of homes just of Westbrook’s Fairway Drive.

Mayor Don Iveson gave a grim laugh. “That’s where I live, right in there,” he said, pointing to a red patch on the south side. The red means water could get 0.75 metres deep.

“My house is actually in a flooded area, too,” said Ward.

“Ward 6 has lots of red,” said Coun. Scott McKeen, looking for advice on what to say if residents call him “freaking out.”

1-in-100-year flash flood predictions for south central EdmontonCity of Edmonton

McKeen was told councillors could sit down with staff to talk neighbourhood by neighbourhood. The release of these maps will kick-start broader conversation on how fast to move on an estimated $2.4 billion in capital flood mitigation projects and what cost versus level of risk citizens are willing to bear. That plan is coming to the utility committee in the spring of 2017.

The maps cover more than 100 neighbourhoods built before 1989. They exclude Mill Woods, where significant flood mitigation work has already been done based on 2004 and 2012 flood data. They also exclude new areas, where the road network is designed to carry water to a safe storage place during a 1-in-100-year flood.

In flood-prone southeast Lauderdale Wednesday, the maps held no surprise.

Edna Carnegie near her home in Lauderdale, where flooding happens as a result of heavy rain.Larry Wong /
Postmedia

Resident Bill Monro was happy to see it. “Insurance companies know this already but ordinary people don’t,” he said.

He lives in a red zone on the map and gets water in his basement regularly. He’s seen water pooling up over the sidewalks during bad rainstorms, and that’s without getting a 1-in-100-year storm. “This whole area would be a lake.”

His neighbour, Edna Carnegie, agreed. She often watches water back up in the alley beside her house.

“It can go right across the street if it’s heavy enough. … And it doesn’t go away fast if the drains are plugged,” she said, wondering what can be done.

“This house was built on a slough and our basement is caving in. Our whole house is caving in,” she said of the home she’s lived in for 45 years. She thinks it will be a teardown when she and her husband sell.

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